Before BLAST, don't split fasta file all the time

Module BLAST, function *blastn* was spliting all input FASTA files so
accelerate a BLAST.

I happened even though the input FASTA consisted of few FASTA sequences. It
now checks that it happens when the input file has more than 399 sequences.
BLAST: splitting input FASTA files

If the FASTA file doesn't need to be splitted, then don't remove the original
file!
v0.3.6

And adding changelog to file CHANGES.txt